WASHINGTON — The Catholic vote is “too close to call,” a survey from a Catholic research center at Georgetown University indicates.

“The vote of Catholics remains quite evenly split: 47% for President Obama and 45% for Gov. Romney,” CARA (The Center for Applied Research in the Apostolate) reported Sept. 17.

The statistically tied candidates have rarely topped 50% of the Catholic vote. The small percentage of Catholic registered voters will likely decide the winner of the Catholic vote in a country where one in four voters is Catholic.

CARA aggregated data from polls that surveyed a Catholic subgroup, including Pew, Gallup and TIPP.

Among Protestants, Romney leads the president by 51% to 40%. Those without a religious affiliation largely favor the president, with 63% saying they will vote for him and only 27% stating they will vote for Romney.

Obama has led Romney by nine percentage points once in March and once in July, while the Republican nominee had his biggest lead of five percentage points in April.

Catholic voters have long been considered an important voting bloc because the presidential candidate who wins over the majority of Catholic voters generally wins the election. However, some commentators question whether the “Catholic vote” exists, given the divisions among Catholics.

According to CARA’s statistics from 2012, there are more than 78 million people in the United States that self-identify as Catholics. The Official Catholic Directory lists that number as just over 66 million.

The percentage of adult Catholics who attend Mass once a week is 24%, or almost 19 million, according to CARA statistics.

The Nov. 6 presidential election is expected to be very close, with the two candidates vying to win every percentage point of the electorate they can to their corner.